1. Field of the Invention
The present invention relates to an image capturing device, a color measurement apparatus, and an image forming apparatus.
2. Description of the Related Art
Color measurement apparatuses that measure colors of patterns (patches), which are formed on a recording medium by an image forming apparatus using coloring material such as ink, by capturing an image of the patterns using a two-dimensional (2D) image sensor to obtain RGB values of the patterns and converting the RGB values into colorimetric values (color measurement values) in a standard color space are conventionally known. An example of such a color measurement apparatus is known from Japanese Laid-open Patent Application No. 2013-224924.
However, color measurement apparatuses of this type can suffer from a problem that, if light specularly reflected off an image capture area of the 2D image sensor impinges on the 2D image sensor, the 2D image sensor can capture an image undesirably including a defective image created by the specularly reflected light, which can exert a negative effect on color measurement of patterns. To alleviate this problem, the color measurement apparatus disclosed in Japanese Laid-open Patent Application No. 2013-224924 arranges, at a position directly under an illumination light source, a diffusing plate that diffuses light emitted from the illumination light source in directions other than toward a 2D image sensor, thereby preventing light specularly reflected off an image capture area of the 2D image sensor from impinging on the 2D image sensor.
However, a color measurement apparatus configured to diffuse light emitted from an illumination light source with a diffusing plate arranged at a position directly under the illumination light source as in the color measurement apparatus disclosed in Japanese Laid-open Patent Application No. 2013-224924 can suffer from a problem that bright reflection light reflected from ridgelines of the diffusing plate impinges on the 2D image sensor and exerts a negative effect on color measurement of patterns.